In raising livestock and in meat packing, it is frequently necessary to dispose of the bodies of animals that die prematurely due to various causes. U.S. Pat. No. 6,703,234, granted on Mar. 9, 2004, for example describes a method and apparatus for composting animal bodies in which odors and pathogens are controlled by recirculation of air and gaseous products of the composting process.
Compost produced from animal carcasses, animal waste, vegetation, garbage, and other materials can be utilized as fertilizer. It is known to use a rotatable digesting drum in which material is introduced, mixed by rotation, and converted into usable fertilizer. In some cases, the composting operation is carried out as a batch process. In others, material is processed in the rotating drum continuously.
One of the problems encountered in continuous composting using a rotating drum is that of introducing material into the drum. Suitable automatic conveyors are expensive, and it is difficult to ensure reliable operation. On the other hand, manual introduction of material is both labor-intensive and unpleasant, and introduction of materials into a rotatable composter using machinery such as a front end loader is difficult especially because of the problem of avoiding spillage.
Another problem is that some materials, such as animal bones and some vegetable matter, will take longer to digest, and must be separated from the composted material in order to deliver a usable product.
Some composting applications can cause corrosion and premature deterioration of conventional composting equipment, necessitating frequent maintenance, and also early replacement of the rotating drum, which is the main component of the composter. Another problem is that composting material tends to slip on the side wall of a rotating drum, resulting in failure of composting media to turn over as desired. Another problem is that some compositing materials adhere to the wall of the rotating drum, resulting in non-uniform transit of material through the drum in a continuous composting operation.
Another problem with a large composter, which can have a length of twelve or more meters and a diameter of three or more meters, is in configuring the composter drum so that it has adequate strength to sustain the weight of its contents without excessively increasing the weight of the drum itself. Still another problem is metal fatigue due to stresses resulting from the weight of the composter drum and its contents.